Metal strip straightening machine

ABSTRACT

The present invention relates to an apparatus for correcting warps such as gutter and curl in a metal strip. The apparatus comprises a small roll which is preceeded by rolls for correcting defects in the shape of the metal strip such as edge wave, full center and quarter buckle and said small roll is followed by at least one medium roll. The small and medium rolls are supported by a film of pressurized liquid and the rolls rotate freely in contact with the moving metal strip, which is bent under tension by said small and medium rolls. The gutter and curl defects are thus each completely eliminated independently of the other.

United States Patent [191 Kawaguchi et al.

[451 Sept. 10, 1974 METAL STRIP STRAIGHTENING MACHINE [73] Assignee: Toyo Kohan Co., Ltd., Tokyo, Japan [22] Filed: Sept. 12, 1973 [21] Appl. No.: 396,365

[30] Foreign Application Priority Data Apr. 24, 1973 Japan 48-45740 [52] U.S.' Cl. 72/163, 72/165 [51] Int. Cl B21d 1/02 [58] Field of Search 72/160-165 [56] References Cited UNITED STATES PATENTS 3,064,509 ll/l962 Ford et al. 72/6 Polakowski 72/ 163 Polakowski 72/ l 63 Primary Examiner-Milton S. Mehr Attorney, Agent, or Firm-Wenderoth, Lind & Ponack [5 7] ABSTRACT The present invention relates to-an apparatus for correcting warps such as gutter and curl in a metal strip. The apparatus comprises a small roll which is preceeded by rolls for correcting defects in the shape of the metal strip such as edge wave, full center and quarter buckle and said small roll is followed by at least one medium roll. The small and medium rolls are supported by a film of pressurized liquid and the rolls rotate freely in contact with the moving metal strip, which is bent under tension by said small and medium rolls. The gutter and curl defects are thus each completely eliminated independently of the other.

5 Claims, 2 Drawing Figures PATENIEUSEPIOIHM I 3384.202

METAL STRIP STRAIGIITENING MACHINE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved straightening machine which straigtens a metal strip. More specifically, the invention is directed to an improvement of an apparatus for correcting warps such as gutter and curl remaining in a metal strip after certain defects in the strips shape have been straightened by a tension leveler.

The machine for correcting the defects in the shape of a thin metal strip such as edge wave, full center and quarter buckle works in such a manner that the metal strip is bent by thrusting work rolls against it and plastically elongating the strip and is known as a tension leveler. After local defects in the shape of the metal strip are corrected by the tension leveler, the defects of gutter and curl remain. The combined gutter and curl warp distort the metal strip such that a perfectly flat metal strip cannot be obtained. The term curl refers to a longitudinal warp of a metal strip due to bending which occurs at the work roll and the term gutter refers to a transverse warp due to restriction of the metal strip in the contact area between the metal strip and the work roll.

2. Description of the Prior Art In order to correct gutter in metal strip the prior art devices provide a roll following the work rollsof a tension leveler and the vertical position of said roll against the metal strip is adjusted appropriately. On the other hand, curl is corrected by a conventional roller leveler which is installed in addition to the tension leveler. Such a conventional way of correcting warps of the metal strip requires an additional large expenditure for installation costs. Moreover, it is difficult to correct warps in certain hard metal strips for example, strips thinner than 0.15 mm and having a tensile strength greater than 60 kglmm A work roll having a smaller diameter than the roll of the conventional roller leveler is conventionally used in the tension leveler to straighten thin and hard metal strip. In such a case, the metal strip is bent by the roll which has a small radius of curvature and restricted strongly at the contacting area with the surface of the work roll, and as a consequence of this procedure the amount of curl and gutter in the metal strip become large.

Accordingly, the conventional prior art apparatus, having rolls of a standard diameter could not correct gutter in a thin and hard metal strip of high tensile strength. It is necessary to use rolls of smaller diameter to achieve sufficient effect. In the conventional way of supporting a small roll by backup rolls stains occur on the surface of the metal strip as a result of lubricating oil which leaks from bearings of the backup rolls onto metal strip and scratches on the strip occur due to slippage between the roll and the metal strip. This lowers the quality of the metal strip which is being treated by the system to correct effect of gutter.

Though gutter is corrected in this way, the conventional roller leveler cannot correct the remaining curl because the radius of the curvature of the curl is extremely small and the metal strip is both hard and thin.

The performance of a prior art tension leveler is thus limited and cannot adequately eliminate warps such as gutter and curl when the metal strip is relatively thin and has a relatively higher tensile strength.

There are several patents which exemplify the prior art. One of them is U.S. Pat. No. 3,270,543. In this patent, a series of rolls are provided in order of increasing diameter from the entrance to the exit of the device. Accordingly, the function of correcting defects in the metal strips shape of the edge wave and so on is not separated from that of correcting warps such as gutter and curl. While it is only necessary to change the amount of plastic elongation to correct defects such as edge wave and so on; the amount of gutter and curl inevitably changes and requires further manipulation. Consequently, the correcting of gutter and curl cannot be achieved independently of the correcting of shape defects such as edge wave and so on.

Another prior art device is shown in Japanese Patent Publication No. 46-l5,4l7 for a machine for straightening warps such as gutter and curl. In this apparatus, the amount of plastic elongation can be changed independently for correcting warps such as gutter and curl. However gutter and curl cannot be corrected simultaneously and it is also difficult to correct gutter in extremely thin and high tensile strength metal strips.

Another prior art device is shown in Japances Patent Publication No. 47-38,734 which discloses a tension leveler in which the diameter of work rolls used for plastically elongating the metal strips is larger than that of the rolls used for correcting warps such as gutter and curl. Contrary to this device, the present invention discloses a tension leveler, which for maximum performance uses extremely small work rolls to correct defects such as edge wave and so on in thin and high tensile strength metal strips.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus for correcting gutter in hard metal strips which are thinner than 0.15 mm and which have a tensile strength of greater than 60 kg/mm Another object of the invention is to provide an apparatus for correcting curl in metal strips without using a conventional roller leveler.

A further object is to provide an apparatus equipped with a tension leveler for simultaneously correcting gutter and curl in a thin hard metal strip, which develop after defects such as edge wave and so on are corrected by the tension leveler.

A further object is to provide a compact apparatus for correcting warps, in which a mechanism is not required to drive the rolls for correcting warps.

The objects are achieved by the apparatus of the present invention which comprises a small diameter roll for correcting warps, which diameter is less than twice the diameter of the work rolls which correct defects such as edge wave and so on by plastically deforming the metal strip. The small roll is positioned behind the last work roll, at least one medium roll for correcting warps is also incorporated in the device. The medium roll has a diameter in the range of two to seven times the diameters of the work rolls. In order to adjust the wrap angle of the metal strip along the small roll and the medium rolls a mechanism for independently adjusting the position of these rolls is provided. Gutter in the metal strip which is present therein after being processed by the work roll is corrected by adjusting the position of the small roll so as to eliminate any gutter BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of an apparatus according to the present invention.

FIG. 2 is a side view of another embodiment of the apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a side view of the apparatus. A metal strip 11 moves under tension T1, T2 in the direction U and is bent by work rolls 1, 2 to correct defects such as edge wave and so on, and is plastically elongated in the process. Though, in FIG. 1, only two work rolls 1, 2 are described to correct the defects in the shape of the metal strip, more than two work rolls can be used. The metal strip 11 is bent by a small roll 3 the diameter of which is less than twice the diameter of the work rolls 1, 2 for correcting gutter in the metal strip 11. The efficiency of the gutter correcting system decreases when the diameter of roll 3 is greater than twice the diameter of rolls 1, 2. The small roll 3 is necessarily provided on the side opposite to the last work roll 2 relative to the metal strip 11. In order to support the small roll 3, an apparatus proposed in Japanese Pat. application No. 46-l03,5 I4 is used. Pressurized liquied is supplied seriatim through a conduit pipe 13, a chamber 14 and capillaries 15 into the clearance between a bearing surface 16 of a roll support 6 and the small roll 3. The small roll 3 is supported by a film of pressurized liquid which is located in the clearance along the entire length and the small roll freely rotates out of contact with the bearing surface 16. A slender roll such as the small roll 3 in this invention may bend, and therefore this type of an apparatus must be used to support it. Roll support 6 can be moved vertically by using long screws 8 in order to change the wrap angle of the metal strip 11 along the small roll 3, although other methods are applicable so long as the position of the small roll 3 can be changed.

After being bent by the small roll 3, the metal strip 11 is bent in the reverse direction by medium roll 4, again for correcting warps. The diameter of roll 4 is optimally between 2 and 6 times the diameter of the work rolls 1, 2. In case that the diameter of the medium roll 4 is less than twice the diameter of the work rolls 1, 2, the medium roll 4 creates additional gutter and in case that the diameter of the medium roll 4 is larger than 6 times the diameter of the work rolls 1, 2, the existing curl is uneffected. The medium roll 4 is provided on the side of the metal strip opposite small roll 3. Roll 4 mainly corrects curl and also rotates freely on a pressurized liquid film. Liquid pressurized by a pump is supplied through a conduit pipe 17, a chamber 18 and capillaries l9 seriatim into the clearance between the medium roll 4 and a bearing surface 20 of a roll support 7 which is fixed to a base 12. The wrap angle of the metal strip 11 along the medium roll 4 can be changed by a deflector roll 5 which is vertically movable although any appropriate means can be used to change the wrap angle.

The small roll 3, only corrects gutter of the metal strip 11 which is created by the work rolls 1, 2. Gutter is corrected by adjusting the position of the small roll 3 by means of the long screws 8 such that the remaining gutter after the metal strip 11 passes the medium roll 4 is eliminated. On the other hand, any remaining curl of the metal strip 11 after passing the small roll 3 is corrected by the reverse bending at the medium roll 4. As the diameter of the medium roll 4 is relatively large, gutter is not created anew. Gutter and curl occurring at the work rolls 1, 2 can thus be eliminated by adjusting the wrap angles of the metal strip 11 along the small roll 3 and the medium roll 4, the position of the small roll 3 being regulated in concert with the medium roll 4 so as to ensure the elimination of any gutter of the metal strip 11 after the strip passes the medium roll 4.

FIG. 2 is a side view of another embodiment according to the present invention. In place of the medium roll 4 and the deflector roll 5, a plurality of medium rolls 2] having diameters which are between 2 and 6 times the diameter of one of the work rolls 1, 2 are presented in succeeding order to the metal strip 11 relative to the small roll 3. Each medium roll 21 is entirely supported by a pressurized liquid film in a roll support 23 fixed to a base 35. Liquid is pressurized by a pump and then supplied through a conduit pipe 25, a chamber 26 and capillaries 27 and forms a pressurized liquid film between bearing surfaces 28 of the roll support 23 and the medium roll 21, for correcting warps. In order to change the wrap angle of the metal strip 11 relative to the respective medium roll 21, a plurality of medium roll 22 having diameters between 2% and 7 times the diameter of one of the work rolls 1, 2 are provided in interleaved fashion between and on the side of the metal strip opposite the side occupied by rolls 21. The medium rolls 22 are supported by a pressurized liquid film similar to the manner in which medium rolls 21 are supported. Liquid is pressurized by a pump and is supplied through a conduit pipe 29, a chamber 30 and capillaries 31 and forms a pressurized liquid film between a bearing surface 32 of a roll support 24 and each of the medium rolls 22. Usually the diameter of the rolls 22 are chosen to be larger than that of the rolls 21. The position of the roll support 24 can be vertically adjusted by long screws 33 or by any suitable means so as to make the intermesh between the medium rolls 21, 22 at the near side to the small roll 3 large and the intermesh at the far side of small roll 3 small. Gutter correction is achieved by adjusting the wrap angle of the metal strip 11 along the small roll 3 so that when the metal strip leaves rolls 21, 22, it is free from gutter. The embodiment shown in FIG. 2 requires more rolls than in FIG. 1, but has the advantage of being able to eliminate gutter and curl at the same time over a wider range than the embodiment of FIG. 1.

Examples of results obtained in using the subject invention for correcting gutter and curl are disclosed herein. Various roll diameters are used during the tests. As a result, when using the combinations of the diameters shown in Table l, the apparatus according to the present invention had a wide ability for correcting gutter and curl. When the metal strip was plastically elongated by more than one percent, gutter and curl in the metal strip were completely eliminated.

Table 1 Roll Diameter mm Metal Strip No. Work Work Small Me- Deflector Material Tensile Thickness dium Roll Roll Roll Roll Roll Strength mm 1 2 3 4 5 kg/mm 1 5 5 5 25 Over 85 Steel 65 0.15 2 5 5 5 25 Over 85 Steel 72 0.10 3 5 5 5 25 Over 85 Steel 90 0.18 4 5 5 5 Over 85 Steel 75 0.05

The system of the present invention makes it possible to simultaneously correct gutter and curl in an extremely hard and thin metal strip which cannot be corrected in the conventional way. Scratches seldom occur on the surface of the metal strip due to dust because the pressurized supporting liquid removes the dust. Also for the metal strips having a thickness of more than 0.2 mm and a tensile strength of approximately 40 kglmm the effect of the apparatus according to this invention is remarkable. There is no need to install an extra machine besides the tension leveler for correcting warps such as gutter and curl and therefore the rate of production will increase and the cost of a product will be reduced.

Work rolls 1, 2 are shown in FIGS. 1 and 2, as the apparatus for correcting defects in the shape of a metal strip such as edge wave and so on. However, besides an apparatus proposed by the Japanese Patent Application No. 46-l03,5l4, a conventional mechanical tension leveler can be used to correct such defects.

We claim:

1. An apparatus for correcting warps such as gutter and curl in a moving metal strip which is under tension, comprising:

a small roll having a diameter of less than twice the diameter of one of a plurality of successively positioned work rolls located to receive said metal strip from the last of said work rolls, said small roll being positioned on the side of the metal strip opposite from the last of said work rolls and a wrap angle being defined by the metal strip along said small roll whereby warps such as gutter and curl are eliminated;

support means for rotatably supporting said small roll positioned in operative relationship thereto and comprising a pressurized liquid film;

means for changing the wrap angle of the metal strip along said small roll connected to said small roll;

a medium roll means positioned to receive the metal strip after the strip has passed said small roll, said roll means being provided for the purpose of removing any curl remaining in said metal strip after said metal strip is treated by said work rolls and said small roll and a wrap angle being defined by the metal strip along said medium roll means;

support means for rotatably supporting said medium roll means in operative relationship to said metal strip, said support means comprising a pressurized liquid film; and

a means for changing the wrap angle of the metal strip along said medium roll means operatively connected to said medium roll.

2. The apparatus of claim 1 wherein said medium roll means comprises a medium roll having a diameter of between 2 and 6 times the diameter of one of said pair of work rolls, said medium roll positioned to receive the metal strip after the strip has passed said small roll and being located on the side of the metal strip opposite from said small roll and a wrap angle being defined by the metal strip along said medium roll.

3. The apparatus of claim 2 wherein each of said support means for rotatably supporting said medium roll and said small roll further comprises a roll support having a bearing surface, and being respectively situated in operative relationship relative to each of said small and medium rolls, said supports each having a chamber and capillaries therein in communication with said bearing surfaces pressurized liquid being provided therethrough to the bearing surfaces and regions between said rolls and their respective bearing supports.

4. An apparatus as recited in claim 1 wherein said medium roll means comprises a plurality of first medium rolls, each having a diameter of between 2 and 6 times the diameter of one of a plurality of work rolls, said plurality of first medium rolls being positioned to receive seriatim said metal strip from said small roll and being located on the side of the metal strip opposite from said small roll and a wrap angle defined by the metal strip along said plurality of first medium rolls; and wherein said support means comprises support means for rotatably supporting said plurality of first medium rolls positioned in operative relation thereto and comprising a film of pressurized liquid;

a plurality of second medium rolls, each having a diameter of between 2 /2 and 7 times the diameter of one of said work rolls, said plurality of second medium rolls being interleaved with said plurality of first medium rolls and on the side of the metal strip opposite said plurality of first medium rolls, and wherein said support means comprises support means for rotatably supporting said plurality of second medium rolls positioned in operative relation thereto and comprising a film of pressurized liquid; and said means for changing the wrap angle comprising means for changing the wrap angle of the metal strip along said plurality of first rolls, said means being operatively connected to said plurality of second rolls.

5. The apparatus of claim 4 wherein said support means for rotatably supporting all of said medium rolls and said small roll further comprise roll supports having bearing surfaces respectively situated in operative relationship relative to said small roll and each of said medium rolls, said supports each having a chamber and capillaries therein in communication with said bearing surfaces through which said pressurized liquid is provided to the regions between said rolls and their respective bearing supports. 

1. An apparatus for correcting warps such as gutter and curl in a moving metal strip which is under tension, comprising: a small roll having a diameter of less than twice the diameter of one of a plurality of successively positioned work rolls located to receive said metal strip from the last of said work rolls, said small roll being positioned on the side of the metal strip opposite from the last of said work rolls and a wrap angle being defined by the metal strip along said small roll whereby warps such as gutter and curl are eliminated; support means for rotatably supporting said small roll positioned in operative relationship thereto and comprising a pressurized liquid film; means for changing the wrap angle of the metal strip along said small roll connected to said small roll; a medium roll means positioned to receive the metal strip after the strip has passed said small roll, said roll means being provided for the purpose of removing any curl remaining in said metal strip after said metal strip is treated by said work rolls and said small roll and a wrap angle being defined by the metal strip along said medium roll means; support means for rotatably supporting said medium roll means in operative relationship to said metal strip, said support means comprising a pressurized liquid film; and a means for changing the wrap angle of the metal strip along said medium roll means operatively connected to said medium roll.
 2. The apparatus of claim 1 wherein said medium roll means comprises a medium roll having a diameter of between 2 and 6 times the diameter of one of said pair of work rolls, said medium roll positioned to receive the metal strip after the strip has passed said small roll and being located on the side of the metal strip opposite from said small roll and a wrap angle being defined by the metal strip along said medium roll.
 3. The apparatus of claim 2 wherein each of said support means for rotatably supporting said medium roll and said small roll further comprises a roll support having a bearing surface, and being respectively situated in operative relationship relative to each of said small and medium rolls, said supports each having a chamber and capillaries therein in communication with said bearing surfaces pressurized liquid being provided therethrough to the bearing surfaces and regions between said rolls and their respective bearing supports.
 4. An apparatus as recited in claim 1 wherein said medium roll means comprises a plurality of first medium rolls, each having a diameter of between 2 and 6 times the diameter of one of a plurality of work rolls, said plurality of first medium rolls being positioned to receive seriatim said metal strip from said small roll and being located on the side of the metal strip opposite from said small roll and a wrap angle defined by the metal strip along said plurality of first medium rolls; and wherein said support means comprises support means for rotatably supporting said plurality of first medium rolls positioned in operative relation thereto and comprising a film of pressurized liquid; a plurality of second medium rolls, each having a diameter of between 2 1/2 and 7 times the diameter of one of said work rolls, said plurality of second medium rolls being interleaved with said plurality of first medium rolls and on the side of the metal strip opposite said plurality of first medium rolls, and wherein said support means comprises support means for rotatably supporting said plurality of second medium rolls positioned in operative relation thereto and comprising a film of pressurized liquid; and said means for changing the wrap angle comprising means for changing the wrap angle of the metal strip along said plurality of first rolls, said means being operatively connected to said plurality of second rolls.
 5. The apparatus of claim 4 wherein said support means for rotatably supporting all of said medium rolls and said small roll further comprise roll supports having bearing surfaces respectively situated in operative relationship relative to said small roll and each of said medium rolls, said supports each having a chamber and capillaries therein in communication with said bearing surfaces through which said pressurized liquid is provided to the regions between said rolls and their respective bearing supports. 